1. Ancestral property is defined differently than what the general people perceive. If a title of a property flows for 4 generations being uninterrupted by any partition/sale/settlement/gift deed or will, i.e. from great grandfather to great grand children, then the said property is called ancestral property which can not be inherited by the female great granddaughter if her father has died intestate before the year 2005.
2. Your said sister will be entitled to her parental properties in equal share with all her other siblings.
3. You can not adjust the amount you have spent on her or the amount she has taken loan from you against the value of her inheritance of her parental properties.
4. You can file a money suit claiming refund of the amount she has taken loan from you with interest duly submitting evidence in support of your said claim.
5. You are not no body to 'give her property' at your terms i.e." only whenever she returns our money which she took for their childrens sake ", since she is entitled to her share of the said parental property like you.
6. As explained above, she will not get any share if it is ancestral property and if your father has died intestate before 2005 and otherwise she will get equal share of the parental property along with you.
7. Based on the above, it will be prudent on your part to amicable settle the matter.